Corbel arch
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| Basic principle of corbeled arch design. | Comparison of (right) a corbel arch and (left) a generic "true" stone arch |
A corbel arch (or corbeled / corbelled arch) is an arch-like construction method which uses the architectural technique of corbeling to span a space or void in a structure, such as an entranceway in a wall or as the span of a bridge. A corbel vault uses this technique to support the superstructure of a building's roof.
A corbel arch is constructed by offsetting successive courses of stone at the springline of the walls so that they project towards the archway's center from each supporting side, until the courses meet at the apex of the archway (often capped with flat stones). For a corbeled vault covering the technique is extended in three dimensions along the lengths of two opposing walls.[citation needed]
Although an improvement in load-bearing efficiency over the post and lintel design, corbeled arches are not entirely self-supporting structures, and it is sometimes termed a "false arch" for this reason. Unlike "true" arches, not all of the structure's tensile stresses caused by the weight of the superstructure are transformed into compressive stresses. Corbel arches and vaults require significantly thickened walls and an abutment of other stone or fill to counteract the effects of gravity, which otherwise would tend to collapse each side of the archway inwards.[citation needed]
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[edit] Use in historical cultures
[edit] Maya civilization
Corbeled arches are a distinctive feature of certain pre-Columbian Mesoamerican constructions and historical/regional architectural styles, particularly in that of the Maya civilization. The prevalence of this spanning technique for entrances and vaults in Maya architecture is attested at a great many Maya archaeological sites, and is known from structures dating back to the Formative or Preclassic era. By the beginning of the Classic era (ca. 250 CE) corbeled vaults are a near-universal feature of building construction in the central Petén Basin region of the central Maya lowlands.[1]
[edit] Ancient Greece
The ruins of ancient Mycenae feature many corbel arches and vaults, the "Treasury of Atreus" being a prominent example.
[edit] Ireland
The Newgrange passage tomb has an intact corbel arch supporting the roof of the main chamber, dating from about 3000BC.
[edit] Notes
- ^ Coe (1987), p.65.
[edit] References
- Coe, Michael D. (1987). The Maya, 4th edition (revised), London: Thames & Hudson. ISBN 0-500-27455-X.
